A bomb threat has forced a passenger plane to make an unplanned landing in the Amazon city of Manaus.

The plane's diversion to the city - one of the sites for the 2014 World Cup - disrupted travel plans for people moving through the Eduardo Gomes airport.

A search of the plane didn't turn up any device, local media reported.

Footage filmed on a mobile phone showed passengers queuing up trying to get information.

The plane's diversion also disrupted travel plans for other people moving through the Eduardo Gomes airport in Manaus.

American traveller Bill Jackson said his flight from Manaus to Brasilia was delayed.

"We were supposed to have already been boarded and left. However, we find out that there's been a bomb threat. And the authorities are searching for whatever evidence they can find. Fortunately, there's been no bomb go off. And we hope none does."

Police in Manaus said the TAM Airlines flight took off from Brasilia on Saturday morning, heading to the city of Boa Vista.

A note left in a bathroom in Brasilia's airport claimed that a bomb was on board the jet.

It had already taken off when the note was discovered, so officials sent the plane to Manaus, where it safely landed.